• Journal of Electrochemical Science and Technology
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• v.11 no.2
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• pp.187-194
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• 2020

Two types of sodium cobalt pyrophosphates, triclinic Na_3.12Co_2.44(P₂O₇)₂ and orthorhombic Na₂CoP₂O₇, are compared as high-voltage cathode materials for Na-ion batteries. Na₂CoP₂O₇ shows no electrochemical activity, delivering negligible capacity. In contrast, Na_3.12Co_2.44(P₂O₇)₂ exhibits good electrochemical performance, such as high redox potential at ca. 4.3 V (vs. Na/Na⁺) and stable capacity retention over 50 cycles, although Na_3.12Co_2.44(P₂O₇)₂ delivered approximately 40 mA h g^-1. This is attributed to the fact that Na₂CoP₂O₇ (~3.1 Å) has smaller diffusion channel size than Na_3.12Co_2.44(P₂O₇)₂ (~4.2 Å). Moreover, the electrochemical performance of Na_3.12Co_2.44(P₂O₇)₂ is examined using Na cells and Li cells. The overpotential of Na cells is smaller than that of Li cells. This is due to the fact that Na_3.12Co_2.44(P₂O₇)₂ has a smaller charge transfer resistance and higher diffusivity for Na⁺ ions than Li⁺ ions. This implies that the large channel size of Na_3.12Co_2.44(P₂O₇)₂ is more appropriate for Na⁺ ions than Li⁺ ions. Therefore, Na_3.12Co_2.44(P₂O₇)₂ is considered a promising high-voltage cathode material for Na-ion batteries, if new electrolytes, which are stable above 4.5 V vs. Na/Na⁺, are introduced.

• The Korean Journal of Pharmacology
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• v.32 no.2
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• pp.189-199
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• 1996

Myocardial ${\alpha}_1-adrenoceptors$ have been shown to mediate a biphaslc inotropic response that was characterized by a transient decline followed by a sustained increasing phase in guinea pig ventricular muscle. Recently one group reported that an ${\alpha}_1-adrenoceptors-induced$ intracellular $Na^+$ decrease is linked to fast $Na^+$ channel inhibition and another group reported that it is linked to $Na^+$-$K^+$ pump activation by ${\alpha}_{1b}-adrenoceptors$. But until now, its mechanism is not clear. Therefore, to see whether the $Na^+$channel or $Na^+-K^+$ pump is related to a decrease in intracellular $Na^+$ activity and/or the negative inotropic response, and which ${\alpha}_1-adrenoceptor$ subtype was involved in the decrease in intracellular $Na^+$activity by phenylephrine, we used conventional and sodium selective microelectrodes, and tension transducer to determine the effects of ${\alpha}_1-adrenergic$ stimulation on membrane potential, intracellular $Na^+$ activity, and twitch force in guinea pig ventricular muscles. $10^{-5}$ M Phenylephrine produced a slight hyperpolarization of the diastolic membrane potential, a decrease or increase in $a_N^i_a$, and a biphasic inotropic response. The negative inotropic response accompanied by a decrease in intracellular $Na^+$activity, whereas in muscles showing a remarkable positive inotropic response without initial negative inotropic effect was accompanied by an increase in intracellular $Na^+$ activity. The decrease in intracellular $Na^+$ activity was apparently inhibited by WB4101, an antagonist of the ${\alpha}_{1a}-adrenoceptors$. The decrease in intracellular $Na^+$ activity caused by phenylephrine was not abolished or reduced by a block of the fast $Na^+$ channels. $V_{max}$ also was not affected by phenylephrine. Phenylephrine produced an increase in intracellular $Na^+$ activity in the presence of a high concentration of extracellular $Ca^{2+}$ (in quiescent muscle) or phorbol dibutyrate, a protein kinase C activator(in beating muscle). These suggest that the ${\alpha}_{1a}-adrenoceptors-mediated$ decrease in intracellular $Na^+$ activity may be related to the protein kinase C.

• Journal of Life Science
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• v.17 no.2 s.82
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• pp.174-178
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• 2007

Treatment of malformin A1 is known to increase ethylene production 130% at 4 hr and 56% at 8 hr after treatment in maize root compared to untreated plants. The ethylene production by malformin A1 was maximum level at 4 hr and slowly decreased up to 8 hr. Calcium ion regulators such as A23187 (calcium ionophore) and verapamil (calcium channel blocker) stimulated ethylene production. Treatment of both calcium ion regulators increased about 30% of ethylene production at 4 hr, and 20% at 8 hr. Both calcium ion regulators did not stimulate malformin A1-induced ethylene production at 4 hr as malformin A1 itself did. However, the treatment of calcium ion regulators with malformin A1 maintains the ethylene production for 8 hr. These results suggested that the proper concentration of calcium might need to confer the effect of malformin A1 on the ethylene production. Malformin A1 suppressed the gravitropic curvature of maize root about 58% at 4 hr and 42% at 8 hr compared to control plant. Verapamil inhibited the gravitropic curvature about 54% at 4 hr and 23% at 8 hr compared to control, respectively. But A23187 could not. In addition, verapamil showed more inhibition in malformin A1-induced gravitropic curvature than A23187 in malformin A1 induced. These data suggested that calcium ion regulators affect the malformin A1-induced ethylene production and gravitropic curvature, and give the evidence that calcium ion play an important role in gravitropic curvature in maize root.

• The Korean Journal of Physiology and Pharmacology
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• v.27 no.6
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• pp.521-531
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• 2023

Transmembrane protein TMEM16A, which encodes calcium-activated chloride channel has been implicated in tumorigenesis. Overexpression of TMEM16A is associated with poor prognosis and low overall survival in multiple cancers including lung adenocarcinoma, making it a promising biomarker and therapeutic target. In this study, three structure-related sesquiterpene lactones (mecheliolide, costunolide and dehydrocostus lactone) were extracted from the traditional Chinese medicine Aucklandiae Radix and identified as novel TMEM16A inhibitors with comparable inhibitory effects. Their effects on the proliferation and migration of lung adenocarcinoma cells were examined. Whole-cell patch clamp experiments showed that these sesquiterpene lactones potently inhibited recombinant TMEM16A currents in a concentration-dependent manner. The half-maximal concentration (IC50) values for three tested sesquiterpene lactones were 29.9 ± 1.1 µM, 19.7 ± 0.4 µM, and 24.5 ± 2.1 µM, while the maximal effect (E_max) values were 100.0% ± 2.8%, 85.8% ± 0.9%, and 88.3% ± 4.6%, respectively. These sesquiterpene lactones also significantly inhibited the endogenous TMEM16A currents and proliferation, and migration of LA795 lung cancer cells. These results demonstrate that mecheliolide, costunolide and dehydrocostus lactone are novel TMEM16A inhibitors and potential candidates for lung adenocarcinoma therapy.

• Biotechnology and Bioprocess Engineering:BBE
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• v.9 no.2
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• pp.132-136
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• 2004

The LAL (Limulus amebocyte lysate) test for the detection and quantification of endotoxin is based on the gelation reaction between endotoxin and LAL from a blood extract of Limulus polyphemus. The test is labor intensive, requiring dedicated personnel, a relatively long reaction time (approximately 1 h), relatively large volumes of samples and reagents and the detection of the end-point is rather subjective. To solve these problems, a miniaturized LOC (lab-on-a-chip) prototype, 62mm (L) ${\times}$ 18 mm (W), was fabricated using PDMS (polydimethylsiloxane) bonded to glass. Using this prototype, in which 2mm (W) ${\times}$ 44.3mm (L) ${\times}$ 100 $\mu\textrm{m}$ (D) microfluidic channel was constructed, turbidometric and chromogenic assay detection methods were compared, and the chromogenic method was found the most suitable for a small volume assay. In this assay, the kinetic-point method was more accurate than the end-point method. The PDMS chip thickness was found to be minimized to around 2 mm to allow sufficient light transmittance, which necessitated the use of a glass slide bonding for chip rigidity. Due to this miniaturization, the test time was reduced from 1 h to less than 10 min, and the sample volume could be reduced from 100 to ca. 4.4 ${\mu}$L. In summation, this study suggested that the LOC using the LAL test principle could be an alternative as a semi-automated and reliable method for the detection of endotoxin.

• Journal of Ginseng Research
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• v.44 no.3
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• pp.490-495
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• 2020

Background: Ginsenoside Rk1, a saponin component isolated from heat-processed Panax ginseng Meyer, has been implicated in the regulation of antitumor and anti-inflammatory activities. Although our previous studies have demonstrated that ginsenoside Rg3 significantly attenuated the activation of NMDA receptors (NMDARs) in hippocampal neurons, the effects of ginsenosides Rg5 and Rk1, which are derived from heat-mediated dehydration of ginsenoside Rg3, on neuronal NMDARs have not yet been elucidated. Methods: We examined the regulation of NMDARs by ginsenosides Rg5 and Rk1 in cultured rat hippocampal neurons using fura-2-based calcium imaging and whole-cell patch-clamp recordings. Results: The results from our investigation showed that ginsenosides Rg3 and Rg5 inhibited NMDARs with similar potencies. However, ginsenoside Rk1 inhibited NMDARs most effectively among the five compounds (Rg3, Rg5, Rk1, Rg5/Rk1 mixture, and protopanaxadiol) tested in cultured hippocampal neurons. Its inhibition is independent of the NMDA- and glycine-binding sites, and its action seems to involve in an interaction with the polyamine-binding site of the NMDAR channel complex. Conclusion: Taken together, our results suggest that ginsenoside Rk1 might be a novel component contributable to the development of ginseng-based therapeutic treatments for neurodegenerative diseases.

• Journal of Biomedical Engineering Research
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• v.19 no.1
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• pp.19-24
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• 1998

The main goal of this paper is to propose and to test a radio protocol based CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) for the purpose of enhancing the existing medical information system. The feature of the new medical information system, Medical Application Radio System(MARS), which operating in real time is the transmission of medical information in bi-direction between the hospital control office and patients mobile stations. MARS monitors patients linked to the network by radio and provides quick alarm, flexible documentation capabilities, asnd fast treatment for the analysis of collected medical data. The existing medical information system, radio telemetry system which transfers the message of patients to the CAP(Central Access Point) unit in one way at the speed of 9.6Kbps and operates a channel frequency bandwidth. To verify the Performance of the proposed system, we have performed the numerical analysis and have implemented a test system which consists of the 2.4Ghz radio transceiver and personal computer.

• Biotechnology and Bioprocess Engineering:BBE
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• v.10 no.4
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• pp.309-314
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• 2005

We performed a basic experiment for the rapid, on-line, real-time measurement of hepatitis B surface antigen using a surface plasmon resonance biosensor. We immobilized anti­HBsAg (hepatitis B surface antigen) polyclonal antibody, as a ligand, to the dextran layer on a CM5 chip surface that had previously been activated by N-hydroxysuccinimide. A sample solution containing HBsAg was fed through a microfluidic channel, and the reflecting angle change due to the mass increase from the binding was detected. The binding characteristics between HBsAg and its polyclonal antibody followed the typical monolayer adsorption isotherm. When the entire immobilized antibody had interacted, no additional, non-specific binding occurred, suggesting the immunoreaction was very specific. The bound antigen per unit mass of the antibody was independent of the immobilized ligand density. No significant steric hindrance was observed at an immobilization density of approximately $17.6 ng/mm^2$. The relationship between the HBsAg concentration in the sample solution and the antigen bound to the ligand was linear up to ca. $40{\mu}g$/mL. This linearity was much higher than that of the ELISA method. It appeared the anti­gen-antibody binding increased as the immobilized ligand density increased. In summary, this study showed the potential of this SPR biosensor-based method as a rapid, simple and multi­sample on-line assay. Once properly validated, it may serve as a more efficient method for HBsAg quantification for replacing the ELISA.

• Journal of Plant Biotechnology
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• v.34 no.3
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• pp.213-221
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• 2007

The treatment of radish cotyledons with a nitric oxide (NO)-releasing substance, sodium nitroprusside (SNP) resulted in an increased adventitious root development in a dose-dependent manner. However, this NO-mediated enhancement effect was reversed when either 0.5 mM EGTA (an extracellular $Ca^{2+}$ chelator) or 0.1 mM $LaCl_3$ (a calcium channel blocker) was applied with $50\;{\mu}M$ SNP. Our results also showed that guaiacol peroxidase (GPX) and syringaldazine peroxidase (SPX) activities, which are known to play a key role in rooting, were more largely increased during adventitious root induction in the cotyledons treated with SNP. However, the treatment of cotyledons with SNP plus $LaCl_3$ inhibited the SNP-induced increases in the activities of both GPX and SPX. Trifluoperazine (TFP), an antagonist of calmodulin (a specific calcium-binding protein), also delayed adventitious root formation and significantly reduced the root length and number of the SNP-treated cotyledons as well as the deactivation of GPX and SPX enzymes. In conclusion, our results suggest that calcium is involved in the NO response leading to induction of adventitious root through a regulation of GPX and SPX.

• Journal of Chest Surgery
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• v.25 no.4
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• pp.364-382
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• 1992

In order to investigate the effect of intracellular cyclic GMP on the calcium channel, whole cell patch clamp technique with internal perfusion method was used in the single ventricular myocytes of the rabbit. Cyclic GMP, cGMP analogues, cAMP, isopernaline and forskolin were perfused into cells and their effects on the calcium current were analysed by applying depolarizing step pulse of 10 mV in amplitude for 200 msec from holding potential of -40 mV. Calcium currents usually activated from -30 mV and then reached a peak at +10 mV. Amplitude of the calcium current was standardized with membrane capacitance, 50 pF. Peak amplitude at +10 mV in control was -0.15 nA/50pF. When 100 mM cAMP was applied from the pipette, peak amplitude of calcium current increased to -0.32 nA and addition of 1 mM isoprenaline further increased its amplitude. In the presence of cGMP it alone also produced an increase of the calcium current to -0.52 nA/50pF and addition of isoprenaline or forskolin increased its magnitude to -[0.55~0.95] nA/50pF. Simultaneous application of cGMP and cAMP increased the calcium current to -0.67 nA/50pF. Among the cGMP analogues, 8-Br-cGMP was the most potent stimulant for the calcium current activation. From the above results it could be concluded tlat cGMP increases the calcium current not through cAMP dependent protein kinase nor cAMP dependent phosphodiesterase pathway, but through independent phosphorylation pathway, possibly cGMP dependent protein kinase pathway.